Continuum robots

Abstract

A continuum robot comprising: a first segment defining a first end and a second end, the first segment including a first actuator coupled to the second end and configured to control movement of the second end relative to the first end; and a first elastic strain sensor coupled to the first segment and positioned between the first end and the second end, the first elastic strain sensor being configured to provide a first output signal associated with the movement of the second end relative to the first end.

We claim: 
     
         1 . A continuum robot comprising:
 a first segment defining a first end and a second end, the first segment including a first actuator coupled to the second end and configured to control movement of the second end relative to the first end; and   a first elastic strain sensor coupled to the first segment and positioned between the first end and the second end, the first elastic strain sensor being configured to provide a first output signal associated with the movement of the second end relative to the first end.   
     
     
         2 . A continuum robot as claimed in  claim 1 , wherein the first segment includes a first disk at the first end of the first segment, a second disk at the second end of the first segment, the first elastic strain sensor being positioned between the first disk and the second disk, the first actuator being coupled to the second disk and configured to control movement of the second disk relative to the first disk, the first elastic strain sensor being configured to provide a first output signal associated with the movement of the second disk relative to the first disk. 
     
     
         3 . A continuum robot as claimed in  claim 1 , wherein the first elastic strain sensor comprises a conductive elastic material. 
     
     
         4 . A continuum robot as claimed in  claim 1 , wherein the first elastic strain sensor comprises a non-conductive elastic vessel defining a cavity, and a conductive material positioned within the cavity. 
     
     
         5 . A continuum robot as claimed in  claim 4 , wherein the conductive material positioned within the cavity comprises a conductive liquid. 
     
     
         6 . A continuum robot as claimed in  claim 5 , further comprising a plurality of fibres positioned within the cavity of the non-conductive elastic vessel. 
     
     
         7 . A continuum robot as claimed in  claim 1 , wherein the first elastic strain sensor comprises a first conductive elastic member, a second conductive elastic member, and a non-conductive elastic member positioned between the first conductive elastic member and the second conductive elastic member. 
     
     
         8 . A continuum robot as claimed in  claim 1 , further comprising a flexible backbone extending through the first segment and between a first disk and a second disk of the first segment, a gap being defined between the flexible backbone and the first elastic strain sensor. 
     
     
         9 . A continuum robot as claimed in  claim 8 , wherein the first disk and the second disk define a perimeter of the first segment, the first elastic strain sensor being positioned at the perimeter of the first segment. 
     
     
         10 . A continuum robot as claimed in  claim 1 , further comprising a second elastic strain sensor coupled to the first segment and positioned between the first disk and the second disk, the second elastic strain sensor being configured to provide a second output signal associated with the movement of the second disk relative to the first disk. 
     
     
         11 . A continuum robot as claimed in  claim 10 , wherein the first segment defines a longitudinal axis, the first elastic strain sensor and the second elastic strain sensor are positioned to at least partially overlap one another along the longitudinal axis. 
     
     
         12 . A continuum robot as claimed in  claim 11 , further comprising a controller configured to receive the first output signal and the second output signal, and to perform a torsion measurement of the first segment using the received first output signal and second output signal. 
     
     
         13 . A continuum robot as claimed in  claim 10 , wherein the first segment defines a longitudinal axis, the first elastic strain sensor and the second elastic strain sensor are positioned to not overlap one another along the longitudinal axis. 
     
     
         14 . A continuum robot as claimed in  claim 1 , further comprising a controller configured to receive the first output signal from the first elastic strain sensor, and to determine the shape of the first segment using the received first output signal. 
     
     
         15 . A continuum robot as claimed in  claim 14 , wherein the controller is configured to control the first actuator using the determined shape of the first segment to move the second disk relative to the first disk. 
     
     
         16 . A continuum robot as claimed in  claim 1 , further comprising:
 a second segment including a third disk at a first end of the second segment, a fourth disk at a second end of the second segment, a second actuator coupled to the fourth disk and configured to control movement of the fourth disk relative to the third disk; and   a third elastic strain sensor coupled to the second segment and positioned between the third disk and the fourth disk, the third elastic strain sensor being configured to provide a third output signal associated with the movement of the fourth disk relative to the third disk.   
     
     
         17 . A continuum robot as claimed in  claim 1 , wherein the first actuator comprises one or more elastic vessels that are configured to change shape in response to a change in internal pressure, the one or more elastic vessels extend between the first end and the second end of the first segment. 
     
     
         18 . A method of controlling a continuum robot comprising a first segment defining a first end and a second end, the first segment including a first actuator coupled to the second end and configured to control movement of the second end relative to the first end, and a first elastic strain sensor coupled to the first segment and positioned between the first end and the second end, the first elastic strain sensor being configured to provide a first output signal associated with the movement of the second end relative to the first end, the method comprising:
 receiving the first output signal from the first elastic strain sensor;   determining the shape of the first segment using the received first output signal; and   controlling the first actuator using the determined shape of the first segment to move the second end relative to the first end.   
     
     
         19 . Apparatus for controlling a continuum robot as claimed in  claim 1 , the apparatus comprising a controller configured to:
 receive the first output signal from the first elastic strain sensor;   determine the shape of the first segment using the received first output signal; and   control the first actuator using the determined shape of the first segment to move the second end relative to the first end.